A primitive Y chromosome in papaya marks incipient sex chromosome evolution

Many diverse systems for sex determination have evolved in plants and animals. One involves physically distinct (heteromorphic) sex chromosomes (X and Y, or Z and W) that are homozygous in one sex (usually female) and heterozygous in the other (usually male). Sex chromosome evolution is thought to i...

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Bibliographic Details
Published in:Nature 2004-01, Vol.427 (6972), p.348-352
Main Authors: Ming, Ray, Liu, Zhiyong, Moore, Paul H, Ma, Hao, Ackerman, Christine M, Ragiba, Makandar, Yu, Qingyi, Pearl, Heather M, Kim, Minna S, Charlton, Joseph W, Stiles, John I, Zee, Francis T, Paterson, Andrew H
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Alleles
Base Sequence
Biological and medical sciences
Carica - genetics
Carica papaya
Chromosomes
Chromosomes, Plant - genetics
Cloning, Molecular
Contig Mapping
Cytogenetics
Disorders of Sex Development - genetics
Evolution, Molecular
Flowers & plants
Fundamental and applied biological sciences. Psychology
Generalities. Genetics. Plant material
Genes
Genes, Plant - genetics
Genetic Markers
Genetics and breeding of economic plants
Humanities and Social Sciences
letter
Molecular biology
Molecular Sequence Data
multidisciplinary
Mutation
Polymorphism, Genetic
Science
Science (multidisciplinary)
Sex Determination Processes
Sexes
Y Chromosome - genetics
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Summary:Many diverse systems for sex determination have evolved in plants and animals. One involves physically distinct (heteromorphic) sex chromosomes (X and Y, or Z and W) that are homozygous in one sex (usually female) and heterozygous in the other (usually male). Sex chromosome evolution is thought to involve suppression of recombination around the sex determination genes, rendering permanently heterozygous a chromosomal region that may then accumulate deleterious recessive mutations by Muller's ratchet, and fix deleterious mutations by hitchhiking as nearby favourable mutations are selected on the Y chromosome. Over time, these processes may cause the Y chromosome to degenerate and to diverge from the X chromosome over much of its length; for example, only 5% of the human Y chromosome still shows X-Y recombination. Here we show that papaya contains a primitive Y chromosome, with a male-specific region that accounts for only about 10% of the chromosome but has undergone severe recombination suppression and DNA sequence degeneration. This finding provides direct evidence for the origin of sex chromosomes from autosomes.
ISSN:0028-0836
1476-4687
DOI:10.1038/nature02228